Natural gas processing system



NOV. 1, 1966 E HUDSON ETAL 3,282,062

NATURAL GAS PROCESSING SYSTEM Filed March 4, 1966 Valve Cycle Conirol /IO L 42 1 40*" F 7 I L J Inlet Scrubber Pre-Compressor l Direct Heof l Valve Exchange Section 1 Vacuum Pump Liquid Level Control fig KW Q 33 Motor Direct Heat I 4 Outlet 2)? Exchange Sechon l v 3 Liquid Level Comm INVENTORS RAY E.HUDSON O. J. KING ATTORNEYS United States Patent 3,282,662 NATURAL GAS PRUCESSING SYSTEM Ray 1E. Hudson and 0. J. King, (Pdessa, Tex, assignors to Basin Recovery Corporation, Midland, Tern, a corporation of Texas Filed Mar. 4, 1966, $911. No. 531,675 4 Claims. (Cl. 6239) The present application is a continuation-in-part of application Serial No. 490,864, filed September 28, 1965, now Patent No. 3,264,212, and entitled Natural Gasoline Process and Apparatus.

The present invention relates generally to a system for processing natural gas, particularly a direct heat exchange liquid recovery unit.

Accordingly, an object of the present invention is to provide for the removal of liquid hydrocarbons within a direct heat exchange system.

Other objects will become apparent from the ensuing specification and attached drawing, wherein the single figure schematically illustrates system of the present invention.

Raw natural gas, as available at Well head or oil separator, is initially passed through inlet scrubber 11? to remove free liquids. Then, the raw gas is passed along conduit 11 into pre-compressor 12, if a vacuum pump is not used, as further explained hereinafter. From. this point, the gas passes through conduit 13 into control valve(s) 14 for alternative cycling through lines 15 and 15' to identical towers 16 and 16'. While the upper drying sections 18 and 18 of towers 16 and 16' contain a desiccant 1'7, 17' such as molecular sieves which absorb any water present in the raw gas, lower direct heat exchange sections 21} and 21) contain any material 19, 19' which will absorb or give up heat, such as inch diameter steel shot, for example. Obviously, other materials may be equally suited or even more satisfactory. In conventional manner, the reference numerals 42 (42), 44 (44) and 46 (46) designate hold down screens, screen wire separators and bed supports, respectively.

The lower ends 22 and 22' of towers 16 contain liquid level controls 24 and 24 from whence liquefied products are removed through conduits 25, 25 and check valves 26, 26 to product outlet 27 for further processing or storage. With control valve(s) 14 in the position designated by solid lines, partially denuded gas then passes through conduit 28, check valve 29 and conduit 31 into expansion motor 30, which reduces temperature of gas as well as condensing additional liquid product if content of gas is proper. A liquid separator 32 (demister) may be installed in line 31 just ahead of expansion motor 30, if desired. It will be seen, then, that expansion motor 311 is loaded by either the pro-compressor 12, vacuum pump or any other desirable means.

Cooled gas passes from expansion motor 30 through lines 33 and 35'into check valve 34 and then into the bottom of alternate tower 16' where the material in heat exchange section is reduced to approximately the temperature of gas leaving expansion motor 30. As the cold low pressure gas moves up through tower 20', it absorbs the heat in material 19' and returns to near the inlet temperature. The low pressure gas then passes over the desiccant 17 in drying section 18 and re-absorbs the water due to its reduced pressure. This low pressure gas is then passed back along line 15 through control valve(s) 14 to final discharge line 37. A vacuum pump 38, driven by expansion motor 31} may be installed downstream of control valve(s) 14 as an alternate to pre-compressor 12. As illustrated, a valve cycle control 40 driven by motor/ compressor 30 cycles control valve(s) 14.

Alternatively, with control valve(s) 14 in the position designated by dotted lines, gas is cycled through line 15' into upper drying section 18 of tower 16'. Then, partially denuded gas exits tower 16' through conduit 28', check valve 29 and conduit 31 into expansion motor 30. Subsequently, cooled gas leaves expansion motor 3%) through lines 33 and 35 into check valve 34 for introduction into the bottom of tower 16. After low pressure gas is passed through desiccant 17 in drying section 18, it passes back through line 15 into control valve(s) 14 for final discharge through line 37.

Manifestly, variation in processing and alternative positioning of equipment may be employed wtihout departing from the spirit of invention, as defined by the subjoined claims.

We claim:

1. In a natural gas processing system, a direct heat exchange liquid recovery unit, comprising:

(A) first and second towers, each of said towers having a drying and heat exchange section;

(B) compressor means fed by raw gas;

(C) expansion motor means;

(D) control valve means for cycling flow of gas from said compressor to said drying section of said first tower while cycling flow of gas from said drying section of said second tower to exhaust and alternatively cycling flow of gas from said compressor to said drying section of said second tower while cycling flow of gas from said drying section of said first tower to exhaust;

(E) means for conveying gas to and from said heat exchange sections of said first and second towers to and from said expansion motor; and

(F) means for conveying product from the bottom of said heat exchange sections of said first and second towers.

2. A recovery unit as in claim 1, wherein said control valve means is operated by said expansion motor.

3. A recovery unit as in claim 1, including a liquid separator interposed within said means for conveying gas from said heat exchange sections of said first and second towers to said expansion motor.

4. A recovery unit as in claim 1, including an inlet scrubber interposed before said compressor means fed by raw gas.

References (Iited by the Examiner UNITED STATES PATENTS 12/1933 Hasche 6231 7/1943 Downs 208188 

1. IN A NATURAL GAS PROCESSING SYSTEM, A DIRECT HEAT EXCHANGE LIQUID RECOVERY UNIT, COMPRISING: (A) A FIRST AND SECOND TOWERS, EACH OF SAID TOWERS HAVING A DRYING AND HEAT EXCHANGE SECTION; (B) COMPRESSOR MEANS FED BY RAW GAS; (C) EXPANSION MOTOR MEANS; (D) CONTROL VALVE MEANS FOR CYCLING FLOW OF GAS FROM SAID COMPRESSOR TO SAID DRYING SECTION OF SAID FIRST TOWER WHILE CYCLING FLOW OF GAS FROM SAID DRYING SECTION OF SAID SECOND TOWER TO EXHAUST AND ALTERNATIVELY CYCLING FLOW OF GAS FROM SAID COMPRESSOR TO SAID DRYING SECTION OF SAID SECOND TOWER WHILE CYCLING FLOW OF GAS FROM SAID DRYING SECTION OF SAID FIRST TOWER TO EXHAUST; (E) MEANS FOR CONVEYING GAS TO AND FROM SAID HEAT EXCHANGE SECTIONS AND OF SAID FIRST AND SECOND TOWERS TO AND FROM SAID EXPANSION MOTOR; AND (F) MEANS FOR CONVEYING PRODUCT FROM THE BOTTOM OF SAID HEAT EXCHANGE SECTIONS OF SAID FIRST AND SECOND TOWERS. 